That your friend has allowed himself to adopt such a stupid narrative is pitiable. That you have bought into it is shameful - you’re smarter than that.
My friend is no fool. He and all his family have degrees, and most of them are educators and professors. He has also been studying racism and the history surrounding it for decades. It is an issue near and dear to his heart. He made it quite clear that he saw Lincoln's actions as a clever strategy to give him the upper hand in a war he wanted and badly needed. In absence of war, the secession would have become more solid with each passing year as it gained acceptance on both sides. Extended time of peaceable coexistence would definitely have been working against Lincoln.
I am not convinced that what my friend believes is true, but he did get me thinking about the issue from that perspective. The theory has certainly become plausible to me though.